Nickel, lead and antimony distributions between ferrous calcium silicate slag and copper at 1300°C

Abstract

Ferrous calcium silicate (FCS) slag has been proposed as a suitable slag system for continuous copper converting. However, there is little information on the important properties of FCS slag and this must be addressed before such a slag can be properly evaluated for implementation. In this work the slag/metal distribution ratios of lead, antimony and nickel between FCS slag and copper were measured at 1300°C and an oxygen partial pressure of 10–6 atmosphere. They were found to have values of 0·93, 0·54 and 0·98 respectively. These distribution ratios were compared to reported values for calcium ferrite slag and iron silicate slags, both currently used for continuous copper converting, and predicted values for FCS slag under the same conditions. Ferrous calcium silicate slag was found to be a little more than twice as good as calcium ferrite slag at absorbing lead oxide but very similar in its ability to absorb antimony and nickel oxides. However, it was almost five times poorer than iron silicate slag for absorbing lead oxide, a little poorer for nickel oxide but almost four times better for antimony oxide. The activity coefficients of NiO, PbO and SbO1·5 in FCS slag were also calculated and found to be 4·5, 1·4 and 0·6 respectively. In terms of minor element distribution behaviour only, it is concluded that FCS slag warrants closer examination as a replacement for calcium ferrite and iron silicate slags in continuous copper converting.